1. Field of the Invention
The present invention relates to needle assemblies having blunting elements for safe and convenient handling. More particularly, the present invention relates to a needle assembly having a double-ended needle for collecting or delivering fluid samples from or into a patient and which includes blunting elements for the double-ended needle.
2. Description of Related Art
Disposable medical devices having piercing elements are typically used for administering a medication or withdrawing a fluid, such as blood collecting needles, fluid handling needles and assemblies thereof. Current medical practice requires that the fluid containers and needle assemblies used in such systems be inexpensive and readily disposable. Consequently, existing blood collection systems, for example, typically employ some form of durable, reusable holder on which detachable and disposable needles and fluid collection tubes may be mounted. A blood collection system of this nature can be assembled prior to use and then disassembled after use. Thus, these blood collection systems allow repeated use of the relatively expensive holder by merely replacing the relatively inexpensive needle and/or fluid collection tube. In addition to reducing the cost of collecting blood specimens, these blood collection systems also help minimize the production of hazardous medical waste.
A popular design configuration of previously available blood collection systems includes a double-ended needle assembly, an evacuated collection tube, and a holder for maintaining the needle assembly and the collection tube in fixed relation. The double-ended needle assembly, which is also referred to as a cannula, has a bore extending therethrough and a hub near a central region thereof. The evacuated fluid collection tube includes a puncturable stopper at one end thereof. In this type of blood collection system, the holder typically has a housing at one end thereof for receiving the needle assembly. Likewise, the holder also has a hollow body with an opening at an opposite end thereof for receiving the collection tube. The needle assembly is rigidly received within the housing of the holder such that a first end of the needle extends forwardly of the holder for puncturing the vein of a patient. The opposite, second end of the needle extends into the hollow body of the holder. Upon assembly of the blood collection system, the needle assembly is inserted into the housing and the collection tube is inserted through the open end of the hollow body until the second end of the needle pierces the puncturable stopper of the collection tube, thereby allowing fluid communication between the interior of the collection tube and the bore which extends through the needle assembly. To draw a blood specimen from a patient using one of these blood collection systems, the evacuated collection tube is partially inserted into one end of the holder, the first end of the needle is inserted into a patient's vein and the collection tube is fully inserted into the holder such that blood will be drawn through the bore of the needle assembly and into the fluid collection tube. After drawing the specimen, the collection tube is removed so that the blood contained therein can be analyzed and the needle assembly is detached for disposal.
In addition to being capable of accommodating blood collection tubes, the holders of some fluid transfer systems are compatible with fluid containers having a fluid to be injected into a patient. Thus, such holders can be used to inject fluid into, as well as draw blood specimens from a patient.
In order to reduce the risk of incurring an accidental needle-stick wound, protection of the used needle tip becomes important. With concern about infection and transmission of diseases, methods and devices to enclose the used disposable needle have become very important and in great demand. Many arrangements have been designed for protecting used needle tips. For example, U.S. Pat. No. 5,951,520 to Burzynski et al., discloses a self-blunting needle in which a rod or probe-like blunting member is disposed within the bore of a needle cannula having a puncture tip suitable for puncturing tissue. To prevent accidental needle-stick wounds from occurring after use of the device, the blunting member, which is retracted behind the puncture tip when the needle is injected into tissue, can be extended beyond the puncture tip of the needle cannula to effectively blunt the puncture tip and eliminate or at least greatly reduce the risk of accidental needle-stick punctures. Such a device, however, does not provide protection for the second end of the needle at the non-patient end of the assembly.
U.S. Pat. No. 5,810,775 to Shaw discloses a collection assembly which provides for retraction of the intravenous needle at the patient end of the assembly, and further discloses a hinged cap at the open end of the housing of the holder. After drawing a specimen into a collection tube, the collection tube is removed, and the hinged cap is closed over the opening of the holder, thereby activating the needle retraction and blocking access to the second end of the needle at the non-patient end. Activation of the hinged cap and the retraction mechanism requires substantial manipulation by the user and cannot be conveniently accomplished with a single hand, as is ideal for typical phlebotomy practice. Furthermore, the size of the device is relatively large, and the retraction mechanism for the needle can cause splattering of blood when the tip of a used needle is accelerated during retraction, thus potentially exposing health care workers to blood-borne pathogens.
Accordingly, a need exists for a needle assembly which provides for safety blunting of the needle at both the intravenous and the non-patient needle points while minimizing aerosolization of blood particulates that may carry infectious diseases, and which is simple to manufacture, easy to operate and does not occupy a significant amount of disposal space.